Method and apparatus for producing artificial silk

ABSTRACT

268,393. Bemberg Akt.-Ges., J. P. March 27, 1926, [Convention date]. Addition to 260,564. Ammoniacal-copper cellulose solutions, processes for making filaments from; apparatus for making filaments,-To ensure the proper action of the draining roller when spinning euprammonia silk according to the stretchspinning method described in the parent Specification, in which method the silk is collected in a centrifuge, the grip of the roller on the thread is increased by increasing the arc of contact between the thread and the roller 6, as shown in Fig. 1, or alternatively a plurality of gripping rollers 7, 8, Fig. 2, each suitably driven is employed, or the thread is held on to the roller 9, Fig. 3, by a pressure roller 10, or the diameter of the draining roller is increased. The roller may be ribbed or smooth, and may be made of glass or indiarubber. The thread, after leaving the spinning funnel 1, may be acidified by passage through a channel 4 or a bath 5.

' Feb. 14, 1939.

A. HARTMANN T' 2,146,737

METHOD AND APPARATUS FOR PRODUCING AR TIF'ICTAL SILK Original Filed Oct. 30, 1926 Patented Feb. 14, 1939 UNITED STATES ATENT OFFICE DIETHOD AND APPARATUS FOR PRODUCING ARTIFICIAL SILK Original application October 30, 1926, Serial No.

145,159. Divided and this application November 2, 1933, Serial No. 696,310. In Germany November 2, 1925 7 Claims.

The present application constitutes a division of application Serial Number 145,159 of August Hartmann and Gotthard Bauriedel, filed October 30, 1926.

Among the numerous methods of producing artificial silk from cellulose solutions, the viscose process and the cuprammonium process according to the wet stretch-spinning method are the only ones which have finally proved capable of being used technically on a large scale. Whereas however it was possible at an early date in the manufacture of viscose artificial silk to shorten the time and reduce the costs of manufacture by introducing the centrifuge for storing and twisting the filaments, the introduction of the spinning centrifuge to simplify the textile part in the manufacture of cuprammonium silk has met with difficulties.

The centrifuge has the advantage that with it it is possible in one operation to obtain a filament which can be wound onto the reel and is twisted in a manner rendering it immediately capable of being used. In the known technical form of the viscose spinning process, the filament is introduced from above into a spinning centrifuge which is rotating at a suitable rapid speed, the filament, owing to centrifugal force, being thrown against the wall of the drum while being simultaneously twisted and collected there in crlligssed layers in the form of a so-called spinning ca 6.

According to the wet stretch-spinning process the cuprammonium silk is produced in a stretch spinning vessel, called in short a funnel. As is well known a neutral or slightly alkaline bath is used as a rule as a precipitant. The filaments produced in this manner and still containing copper were hitherto collected on reels, rollers, bobbins or the like, and acidified with dilute acid, before or on the reel, roller, bobbin or the like.

Attempts have been made to combine the treatment of a cuprammonium cellulose solution to obtain artificial silk according to the wet stretchspinning process with the advantages of the centrifuging process. For this purpose the filaments produced beforehand in the known stretch-spinning vessels were introduced in a manner corresponding to the viscose process into the spinning drum. The filaments were then acidified with dilute sulphuric acid in various ways in the spinning drum and finished in a known manner. Other experiments have shown that a satisfactory product can be obtained by acidifying the filament before the centrifuge and that under tension. For this purpose a drawing device is inserted between the acidifying device and the centrifuge which on the one hand leads the filament to the centrifuge and on the other hand increases the draught of the centrifuge to ensure the necessary tension.

Accordingly the invention comprises a process for manufacturing twisted artificial silk from cuprammonium cellulose solutions in which the filament after leaving the spinning device is acidified under tension and thereafter is drawn in and twisted by a so-called spinning centrifuge. It also includes the uniform stretching of artificial filaments by the use of a positively driven drawing roller and a rotatable guide roller adapted to be rotated 'by the tension applied to the filaments being stretched by the drawing roller.

Since any acid adhering to the filament is instantaneously thrown out in the centrifuge the acidifying must be ended before the filament enters the centrifuge. To obtain this result surely according to the invention the path of the filament from the spinning vessel to the centrifuge can be extended. This may be done by suitable arrangement of drawing rollers, for instance, by placing the rollers in an elevated position so that the filament firstly raises from the acid bath and then descends again to the centrifuge. It is also possible to lead the filament around the drawing roller and to so elongate the path.

The drawing or delivery rollers may be smooth, ribbed or serrated. They may be made of glass, porcelain, soft or hard rubber and other acidresisting materials, the same applying to any guiding rollers.

In order to obtain a filament'of a uniform titre it is necessary that the filament adheres sufficiently to the drawing device so that it does not slip. This may be obtained by increasing the angle of contact around the roller, by arranging pressure rollers under the action of a weight or spring and so on.

On the drawing a device according to the invention is illustrated in several forms of execution.

Figure 1 shows a device with an elevating drawing roller; and

Figure 2 a device in which the filament surrounds the drawing roller.

In Figure 1 the filament leaves the outlet opening 2 of the spinning apparatus I, passes through under the reversing rod 3 and the guiding roller 5, both of which dip into the vessel 6 filled with dilute sulphuric acid, up to the positively driven delivery roller 1, from which the filament passes through the socalled spinning tube 9 to the spinning centrifuge 8.

In the other constructional form shown in Figure 2 the numerals represent the same parts. The acid vessel 6 has the form however of an inclined gutter upon which fall drops of acid.

Instead of treating the moving filament with acid at the reversing rod 3 or on the way from this rod to the delivery roller 1, a satisfactory result is also obtained if the delivery roller 1 revolves in dilute acid or if acid is allowed to trickle over it, and it is of advantage if some acid runs back along the filament towards the reversing rod 3.

It is preferred to use a filament guide between the drawing roller and the spinning apparatus which is rotatable by the tension of the filaments being stretched. With this arrangement a more uniform stretching is accomplished and also the degree of resistance, which is dependent upon the friction between the roller and its support, may be regulated and maintained uniform to give the desired degree of stretching. For some purposes it may be desired to lead the filaments directly to the freely rotatable guide roller from the spinning apparatus. It is possible to work with one delivery roller alone as a guiding device. In this case the filament running onto the delivery roller may be treated with acid or acid allowed to trickle over it. We may provide the delivery roller 1 with a reversing rod and a rotatable filament guide having a braking action upon the speed at which the filament is taken off, so that the filament is subjected to a definite higher tension between filament guide and delivery roller, and it has been found especially advantageous to acidify the filament at this point and under the tension produced in this way. This. tension can be varied by suitably shaping the filament guide or the reversing rod. This tension can be increased in this way gas desired, but has a definite limit, as the filament may otherwise be damaged by'the numerous friction points.

This apparatus maybe used with the cuprammonium stretch spinning process, the viscose ;process or other processes in which a uniform degree of stretching is desired.

What we claim is:

1. An apparatus for uniformly stretching artificial filaments comprising a spinning nozzle, a

.positively driven drawing roller contacting with the filaments being stretched throughout more than half its diameter, a braking rod between the spinning nozzle and the drawing roller and a guide roller rotatable by the tension of the filaments being stretched positioned between the braking rod and the drawingroller.

2. An apparatus for producing artificial silk fromceliulose solutions by the stretch-spinning process, comprising means for forming the filaments, areversingrod, a rotating guide, a positively driven drawing roller over which the filaments pass without slippage, an acid vessel between said forming means and said drawing roller, and a spinning centrifuge to receive the filaments 3. An apparatus for producing artificial silk from cellulose solutions comprising means for 4. A method for preparing artificial silk com- 7 prising extruding the filaments into a spinningv bath and thereafter applying tension to stretch them by passing them while wet around a positively driven drawing roller with which they have sufiicient length of contact to cause them to move at the same longitudinal speed as the peripheral speed of the drawingroller, causing the filaments at a point between the drawing roller and the spinnerette to move at a slower speed than the peripheral speed of the drawing roller and delivering the filaments from the drawing roller to a collecting unit.

5. An apparatus for preparing artificial silk comprising a spinnerette adapted to extrude a spinning solution into a spinning bath, a collecting device for collecting the artificial silk, a driven roller between the collecting'device and the spinnerette for receiving the threads while wet, said roller having a higher peripheral speed than the. extrusion speed of the filaments, and having sufiicient contact with the thread to prevent slippage between the thread and the surface of the roller, and means interposed between the roller and the'spinnerette for absorbing tension applied to thread by the driven roller.

6. An apparatus for preparing artificial silk comprising a spinnerette adapted to extrude'a spinning solution into a spinning bath, a collecting device for collecting the artificial silk, a driven roller between the collecting device and the spinnerette for receiving the threads while wet, said roller havinga higher peripheral speed than the extrusion speed of the filaments, and having sufiicient contact with the thread to prevent slippage between the thread and the surface of the roller, and braking means interposed between the roller and the spinnerette for absorb ing tension applied'to the thread by thedriven roller. 7

'7. An apparatus for preparing artificial silk comprising a spinnerette adapted to extrude a spinning solution into a spinning bath, a collecting device for collecting the artificial silk, a driven roller between the collecting device and the spinnerette for receiving the threads while wet, said roller having a higher'peripheral speed than the extrusion speed of-the filaments, and

having suificient contact with the thread to prevent slippage between the thread and the -sur face of the driven roller, and braking means interposed between the roller and the spinnerette for absorbing tension applied to the threadby the driven roller said braking means comprising a rod and a freely rotatable guide roller.

AUGUST HARTMANN. GOTTHARD BAURIEDEL. 

